The present invention relates to an endoscope system that is capable of capturing OCT (Optical Coherence Tomography) images of an object such as biotissues as well as normal light and/or fluorescent light images of a surface of the object.
Conventionally, endoscope systems for observing objects inside a human cavity have been known. An endoscope system is generally provided with an endoscope, which is to be inserted inside the human cavity, and an illuminative external device, which is to be connected to the endoscope. The external device includes a light source unit for illuminating the object, and a processor for processing image signals.
The endoscope includes:
an illuminating optical system, which is connected to the light source unit of the illuminative external device and used for illuminating an object (e.g., the paries of a body cavity);
an objective optical system for receiving light from the object and forming an optical image of the object; and
a CCD (Charge Coupled Device) provided substantially at a focal plane of the objective optical system for capturing the object image, the CCD being electrically connected to the processor of the external device.
At a tip end of the endoscope, an instrument opening is formed. Forceps or various kinds of treatment instruments can be inserted through the endoscope, and the tip portion of the inserted instrument is protruded from the instrument opening, inside the human cavity.
With the endoscope system described above, an operator is capable of observing inside the human cavity as described below.
The operator firstly inserts the endoscope inside the human cavity. Light emitted by the light source unit of the external device is projected to an object to be observed through the illuminating optical system. An optical image of the illuminated object is formed, through the objective optical system, on the light receiving surface of the CCD. The CCD converts the received optical image into an electronic image (i.e., image signal), which is transmitted to the processor of the external device. The processor processes the received image signal, and displays the image of the object on a displaying device. Thus, the operator is capable of observing, for example, the paries of the human cavity of a patient by viewing the images displayed on the displaying device.
If the operator judges that there is a possibility of a cancer or a tumor within the observing portion of the human cavity, a forceps or biopsy instrument is inserted in an instrument channel inside the endoscope. The tip portion of the instrument is protruded from the instrument opening, and the tissues of the portion in question can be collected. The tissues thus obtained is subjected to a pathological inspection, and based on the results of the inspection, diagnosis is made.
According to the conventional endoscope system as described above, only the surface (i.e., paries) of the human cavity is observable. In order to know the condition of tissues beneath the paries of the human cavity, biopsy operation is required. In particular, in order to find an early cancer or a small tumor, the biopsy operation is indispensable. However, the pathological inspection requires time, and therefore, the diagnosis requires time.
Further, in view of a burden to the patient, the biopsy can be done only in a limited area and by a limited number of times. Diseased portion may be present at a portion other than the portion identified by the operator. However, such a portion might be overlooked, and as a result, an accurate diagnosis may not be done even if the pathological inspection is performed.
It is therefore an object of the present invention to provide an improved endoscope system which enables an accurate diagnosis within a relatively short period of time.
For the object, according to the present invention, there is provided an endoscope system provided with a normal light image capturing system, a fluorescent image capturing system and an OCT image capturing system. The normal light image capturing system that captures an image of an object inside a human cavity by illuminating the object with white light. The fluorescent light image capturing system captures an image of the object by illuminating the object with excitation light. The object (i.e., human tissues) emits fluorescent light upon incidence of the excitation light. The OCT image capturing system captures an OCT image of a desired portion of the object. The endoscope system is further provided with a display controlling system that controls a displaying device to display the normal light image, the fluorescent light image and the OCT image simultaneously.
Since the operator can view the three different images simultaneously, an accurate diagnosis can be made within a relatively short period of time.
Optionally, at least one of the normal light image and the fluorescent light image is displayed on the displaying device as an animated image.
Further optionally, an OCT scanning line indicating system may be provided to indicate a line representative of a scanning line corresponding to the OCT image on one of the normal light image and the fluorescent light image, which is displayed as the animated image.
With this configuration, the operator can recognize the positional relationship between the normal or fluorescent image of the object and the tomogram thereof. Thus, accurate observation can be expected.
Optionally, the OCT image may also be displayed as an animated image.
According to another aspect of the invention, there is provided an endoscope system, which is provided with an illuminating optical system that selectively emits, toward an object, visible light and excitation light for exciting the object to fluoresce, an objective optical system that converges light from the surface of the object to form an optical image of the surface of the object, an image capturing system that captures an optical image of a surface of the object and generates an image signal corresponding to the optical image. Further, the endoscope system is provided with a first light guide, a second light guide, an optical coupler for optically coupling the first and second light guides. Furthermore, the endoscope system is provided with a low-coherent light source that emits a low-coherent light beam, the low-coherent light source being provided at a proximal end side of one of the first and second light guides, the light emitted by the low-coherent light source being incident on the one of the first and second light guides, a scanning unit that causes the light beam emerged from the first light guide to scan on a predetermined surface of the object, the scanning unit directing the light beam reflected by the object to the first light guide as a detection light beam, a reflector that reflects a light beam emerged from the second light guide to the second light guide as a reference beam, an optical path length adjusting system that relatively changes a length of an optical path length from the optical coupler to the object via the first light guide and an optical path length from the optical coupler to the reflector via the second light guide, a light detecting device provided at a proximal end side of the other of the first and second light guides, the light detecting device detecting an interfered beam generated due to interference between the reference beam and the detection beam, an OCT image forming system that generates a tomogram based on the signal detected by the light detecting device when the optical path length adjusting system and the scanning unit operate, and a video signal generating system that generates video signals of the optical image of the object and the OCT image based on the image signal output by the image capturing system and the OCT image forming system.
With this configuration, since the video signals corresponding to the image of the surface of the object and the tomogram thereof are output, the image of the surface of the object and the OCT image can be viewed with monitoring the positional relationship therebetween.
Optionally, the endoscope system is provided with a display device that displays the optical image of the surface of the object and the OCT image in accordance with the video signals output by the video signal generating system.
In particular, the image capturing system generates a normal light image signal representing the surface of the object when the illuminating optical system emits the visible light toward the object, the image capturing system generates a fluorescent light image signal representing the surface of the object when the illuminating optical system emits the excitation light toward the object, the OCT image forming system outputs an OCT image signal representing the OCT image of the object, and the video signal generating system generates video signals based on the normal image signals, fluorescent image signals and the OCT image signals, and causes the display device to display the normal light image, the fluorescent light image and the OCT image arranged in a predetermined manner.
Preferably, the video signal generating system includes a memory corresponding to a screen of the display device, the memory storing the normal light image signal, the fluorescent light image signal and the OCT image signal.
In particular, the video signal generating system makes the display device display one of the normal light image and the fluorescent light image as an animated image, and wherein the video signal generating system makes the display device display the OCT image as an animated image.
Optionally, the video signal generating system makes the display device display the other one of the normal light image and the fluorescent light image as a still image.
Preferably, the video signal generating system makes the display device display the normal light image as a color image.
Optionally, the video signal generating system includes a cursor generating system that inserts a cursor indicating a scanning position of the scanning unit in the normal light image or the fluorescent light image.
Further optionally, the endoscope system may be provided with a visible light source that emits the visible light, an excitation light source that emits the excitation light, and a light source switching system that selectively causes the visible light and the excitation light to impinge on the illuminating optical system.
Optionally, the optical path length adjusting system moves the reflector toward/away from a tip of the second light guide to vary the optical path length from the optical coupler to the reflector via the second light guide relative to the optical path length from the optical coupler to the object via the first light guide.
In a particular case, the low-coherent light source may include a super-luminous diode.